title: Groin pain after metal on metal hip resurfacing: mid-term follow-up of a prospective cohort of patients.
abstract: OBJECTIVE
  Groin pain after metal on metal hip resurfacing has been previously reported. The purpose of this study was to determine the natural history of a cohort of patients with groin pain after hip resurfacing previously reported on and incidence of revision surgery.
  
  
  METHODS
  Our group previously reported an 18% incidence of groin pain at a mean of 18 months post hip resurfacing. This cohort of groin pain patients was prospectively followed. Patients were evaluated using a visual analog pain rating score, the University of California at Los Angeles (UCLA) Physical Activity Index, and the Western Ontario and McMaster Universities Osteoarthritis (WOMAC) Index. Functional outcome scores were compared from initial to latest follow up using the paired Student's t test. Further diagnostic evaluation and/or intervention or other complication was also recorded.
  
  
  RESULTS
  The latest mean follow up from surgery was 63 ± 15 months. The mean pain rating, UCLA, and WOMAC scores all improved at latest follow up, although WOMAC score improvement was not statistically significant. Mean pain rating score improved from 5.2 ± 2.0 to 2.5 ± 1.4 (p = 0.0001). UCLA activity score improved from 6.4 ± 2.0 to 6.9 ± 1.6 (p = 0.03). Total WOMAC score improved from 75.6 ± 20.5 to 84.5 ± 14.8 (p = 0.15). Only one patient was revised for an adverse local tissue reaction.
  
  
  CONCLUSIONS
  Groin pain post hip resurfacing has a multifactorial etiology, and in the vast majority of cases improves over time with no significant functional limitations. However, the surgeon should be aware of the many potential causes, and help minimize the possibility with proper patient selection and surgical technique.
authors.affiliation: Division of Orthopaedic Surgery, 501 Smyth Road, Room W1650, Ottawa, ON K1H 8L6 Canada.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Illical
authors.forename: Heather
authors.initials: H
authors.lastname: Belanger
authors.forename: Paul R
authors.initials: PR
authors.lastname: Kim
authors.forename: Paul E
authors.initials: PE
authors.lastname: Beaulé
keywords: groin pain; hip resurfacing; metal-on-metal